dev/core#3095 Permit setting of format_locale, prefer if set

dev/core#3095 Permit setting of format_locale, prefer if set

This is a minimal patch to address https://lab.civicrm.org/dev/core/-/issues/3095
in time for 5.47. With this set it is possible to change the format locale to
English, Canada or English, Australian (but not NZ!)
and the currency will only be displayed before dollar amounts NOT of that
currency.

This should be enough to mitigate that regression feeling but missing are
1) fixing the admin form to hide irrelevant settings if format_locale is set
2) the psuedoconstant is cludgey - existing stuff doesn't seem to work so
I added a function - also - if we ARE going to use this option group we
should .... add NZ to it